OBJECTIVE: We address the current classifications and new changes regarding uncommon primary pleural tumors. Primary pleural tumors are divided according to their behavior and are discussed separately as benign tumors, tumors of low malignant potential, and malignant neoplasms. DATA SOURCES: Current literature concerning primary pleural neoplasms was collected and reviewed. STUDY SELECTION: Studies emphasizing clinical, radiological, or pathologic findings of primary pleural neoplasms were obtained. DATA EXTRACTION: Data deemed helpful to the general surgical pathologist when confronted with an uncommon primary pleural tumor was included in this review. DATA SYNTHESIS: Tumors are discussed in 3 broad categories: (1) benign, (2) low malignant potential, and (3) malignant. A practical approach to the diagnosis of these neoplasms in surgical pathology specimens is offered. The differential diagnosis, including metastatic pleural neoplasms, is also briefly addressed. CONCLUSIONS: Uncommon primary pleural neoplasms may mimic each other, as well as mimic metastatic cancers to the pleura and diffuse malignant mesothelioma. Correct diagnosis is important because of different prognosis and treatment implications for the various neoplasms.